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Gearing & Lap Times

Calculate gear inches, rollout, speed and lap times for your gearing.

Calculate your gearing

Select your chainring and sprocket to see your gear inches, ratio and rollout.

Gear inches
108.0″
Gear ratio 4.000 : 1
Rollout 8.384 m

Gear inches use the standard 27-inch track convention. Rollout is based on estimated tyre circumference unless a measured value is entered.

Speed & cadence

Enter either speed or cadence to calculate the other for your selected gearing.

Flying lap time At current speed · 250 m track
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Race & lap timesEstimate an event time using your selected speed and first lap.
Estimated race time—
Average lap time after first—

Model: the first full lap uses your entered time. The remaining race distance uses your calculated steady speed, including any partial final lap. This does not model acceleration, fatigue or changing pace.

Find a gearFind chainring and sprocket combinations for a target time and cadence.

Enter a target lap time and cadence. We will search 48–75T chainrings and 9–20T sprockets, prioritising close ratios and 14–17T sprockets.

Enter a target time and cadence to find matching gears.

Settings250 m track · km/h